The first place to look is in the custom settings section in Salesforce:
- Log into Salesforce and look at the top right corner to find your username. Open the drop-down list and select Setup.
- In the App Setup section on the left, expand Develop then Custom Settings.
- In the Settings list, find the S4S LBPlus Settings entry and click Manage.
- The Site URL/IP must be set to your website to define the end point for S4S LB web service.
Other EXM settings are in Sitecore - see the S4S.config file.